Benzene Homologues Research Articles

Volatile organic compounds (VOCs) emission interferes with real-time regulatory monitoring of ozone in urban atmosphere

Ozone (O3) pollution is a global concern. The real-time ultraviolet (UV) photometric method is commonly employed at the majority of O3 regulatory monitoring stations around the world. High concentrations of volatile organic compounds (VOCs) have been confirmed to interfere with the real-time O3 monitoring by this method. However, it is unknown whether VOCs emission in the urban environment has an impact on the O3 regulatory monitoring. Here we revealed that high VOCs concentration in an urban industrial zone may result in positive artifacts in O3 measurement at a nearby atmospheric monitoring station. These VOCs were dominated by styrene with concentrations at a mg/m3 level, which was closely related to the abnormally higher O3 measurements observed in this station at night. Experimental validation confirmed that benzene homologues could induce evidently O3 measurement artifacts by the regulatory UV photometric method. By equipped with a temperature control system for the O3 measurement scrubber to desorb VOCs adsorbed by O3 the scrubbing catalyst, the O3 measurement artifacts showed an effective decline with a maximum of 30 ppb in the field cases. This study shed light on the improvement of the air quality assessment by coordination of the monitoring stations and approaches in the future.

Release of biogenic volatile organic compounds and physiological responses of two sub-tropical tree species to smoke derived from forest fire

Forests emit a large amount of biogenic volatile organic compounds (BVOCs) in response to biotic and abiotic stress. Despite frequent occurrence of large forest fires in recent years, the impact of smoke stress derived from these forest fires on the emission of BVOCs is largely unexplored. Thus, the aims of the study were to quantify the amount and composition of BVOCs released by two sub-tropical tree species, Cunninghamia lanceolata and Schima superba, in response to exposure to smoke. Physiological responses and their relationship with BVOCs were also investigated. The results showed that smoke treatments significantly (p < 0.001) promoted short-term release of BVOCs by C. lanceolata leaves than S. superba; and alkanes, olefins and benzene homologs were identified as major classes of BVOCs. Both C. lanceolata and S. superba seedlings showed significant (p < 0.005) physiological responses after being smoke-stressed where photosynthetic rate remained unaffected, chlorophyll content greatly reduced and Activities of anti-oxidant enzymes and the malondialdehyde content generally increased with the increase in smoke concentration. Activities of anti-oxidant enzymes showed mainly positive correlations with the major BVOCs. In conclusion, the release of BVOCs following smoke stress is species-specific and there exists a link between activities of antioxidant enzymes and BVOCs released. The findings provide insight about management of forest fires in order to control excessive emission of smoke that would trigger increased release of BVOCs.

Synthesis of hierarchically porous zirconium-based metal-organic framework@silica core-shell stationary phase through etching strategy for liquid chromatography

Metal organic frameworks (MOFs) show promise to be employed as stationary phase for high performance liquid chromatography (HPLC), however, the microporous structures of MOFs seriously restrict the diffusion and mass transfer of solute molecules, leading to a low column efficiency. In this paper, the fabrication of hierarchically porous UiO-66@SiO2 (HP- UiO-66@SiO2) core-shell microspheres via H2O2 etching has been proposed as a viable approach to enhance the separation performance of MOFs-based columns for HPLC. Through the direct treatment of the preliminary prepared UiO-66@SiO2 microspheres with H2O2 etching, HP-UiO-66@SiO2 core-shell microspheres were successfully synthesized with an enlarged pore size of up to 9 nm, facilitating efficient mass transfer in chromatographic separation. The prepared HP-UiO-66@SiO2 core-shell microspheres were then explored as stationary phase in HPLC to separate the nonpolar alkyl benzene homologues, the polar aromatic alcohol homologues and the xylene isomers. The results indicated that the baseline separations of these solutes were achieved successfully with narrow peak width and higher resolution than the UiO-66@SiO2 column. The HP-UiO-66@SiO2 column exhibited superior separation performance, reaching a maximum plate number of 134,459/m for fluorene, and showing good reproducibility. As a result, this template-free approach suggests that the fabrication of hierarchically porous MOFs@silica core-shell microspheres is a successful approach to enhance the column efficiency of MOFs-based columns in HPLC.

Spatiotemporal distribution, source apportionment and health risk assessment of atmospheric volatile organic compounds using passive air samplers in a typical coastal area, China

To fully understand source characteristics and human health effects of atmospheric volatile organic compounds (VOCs), it is of great importance to implement long-term measurements, precise source apportionment and simulation. In this study, a 12-month measurement of VOCs was conducted in a coastal area in East China by a novel passive air sampler (PAS). A total of 28 VOC species, mainly in groups of aromatics and halohydrocarbons were observed. The monthly average concentrations of TVOC were as follows: industrial sites (154.10–727.19 μg m−3) > business sites (65.83–86.96 μg m−3) > residential sites (59.63–60.05 μg m−3) > background site (57.62 μg m−3). Their seasonal variation characteristics were: winter > spring > autumn > summer, which was more apparent at industrial sites due to human activities. Six VOC sources including industrial processes, organic solvents, dyeing, plastic synthesis, traffic emissions, and pesticides identified by the positive matrix factorization model compared favorably with the local emissions at industrial sites. Bromoform, hexachloro-1,3-butadiene, C1–C3 halogenated alkanes and benzene homologs could be the important indicators of industrial VOC emissions. The halohydrocarbons and aromatics were the major contributors to the ozone formation potential (OFP) and secondary organic aerosol potential (SOAP) in industrial areas, respectively. Both of OFP and SOAP have their maximum values in winter due to high VOC concentrations. Health risk assessment indicated that a high probability of non-carcinogenic risk (HI > 1) was in the region at 10 m height and 50m radius, and minor carcinogenic risk (CR > 10−6) was in the region at 70 m height and 1000 m radius. Among all the compounds, 1,2-Dibromo-3-chloropropane was the largest contributor with the individual HI value (17.99) and carcinogenic risk (5.34 × 10−3) at the peak. In this study, the PAS as a sampling tool was proven to be reliable and efficient for long-term measurements in coastal areas. It is worth to have further studies to promote passive sampling as an alternative to VOCs monitoring methods.

Incorporation of metal-organic framework MOFs-5 into the polymer monolith via the surface covalent immobilization method for enhanced capillary liquid chromatographic separation of benzene homologues

In this study, metal organic framework material MOFs-5 was immobilized covalently on the surface of polymer monolith to improve the separation efficiency of small molecular compounds in the mode of capillary liquid chromatography (cLC) firstly. Scanning electron microscopy, fourier transform infrared spectroscopy and flow-through property test were applied to characterize the novel [email protected] monolith, confirming that MOFs-5 was effectively immobilized on the surface of polymer monolith via covalent reactions. More importantly, Benzene homologues (benzene and phenol) which could be separated by the commercialized C18 packed chromatographic column have been well separated via the [email protected] monolith. By contrast, there wasn't any separation between benzene and phenol via the original polymer monolith. Moreover, the relative standard deviation was less than 2.2 % for run-to-run. These results showed that the [email protected] monolith is a kind of potential commercialized material for small molecular compound separation in the mode of cLC.

Transcriptomics and co-expression network analysis revealing candidate genes for the laccase activity of Trametes gibbosa

BackgroundTrametes gibbosa, which is a white-rot fungus of the Polyporaceae family found in the cold temperate zone, causes spongy white rot on wood. Laccase can oxidize benzene homologs and is one of the important oxidases for white rot fungi to degrade wood. However, the pathway of laccase synthesis in white rot fungi is unknown. ResultsThe peak value of laccase activity reached 135.75 U/min/L on the 9th day. For laccase activity and RNA-seq data, gene expression was segmented into 24 modules. Turquoise and blue modules had greater associations with laccase activity (positively 0.94 and negatively -0.86, respectively). For biology function, these genes were concentrated on the cell cycle, citrate cycle, nicotinate, and nicotinamide metabolism, succinate dehydrogenase activity, flavin adenine dinucleotide binding, and oxidoreductase activity which are highly related to the laccase synthetic pathway. Among them, gene_8826 (MW199767), gene_7458 (MW199766), gene_61 (MW199765), gene_1741 (MH257605), and gene_11087 (MK805159) were identified as central genes. ConclusionLaccase activity steadily increased in wood degradation. Laccase oxidation consumes oxygen to produce hydrogen ions and water during the degradation of wood. Some of the hydrogen ions produced can be combined by Flavin adenine dinucleotide (FAD) to form reduced Flavin dinucleotide (FADH2), which can be transmitted. Also, the fungus was starved of oxygen throughout fermentation, and the NADH and FADH2 are unable to transfer hydrogen under hypoxia, resulting in the inability of NAD and FAD to regenerate and inhibit the tricarboxylic acid cycle of cells. These key hub genes related to laccase activity play important roles in the molecular mechanisms of laccase synthesis for exploring industrial excellent strains.

Determination of six benzene homologues in human blood by purge and trap-gas chromatography-mass spectrometry

Objective: To establish a purge and trap-gas chromatography-mass spectrometry method based on soil analysis model for the determination of six benzene homologues (benzene, toluene, ethylbenzene, m-xylene, p-xylene and o-xylene) in human blood. Methods: From September 2020 to May 2021, diatomite was used as a dispersant to add 2.0 ml blood sample and fully mixed. The sample was directly injected into the purging and collecting bottle after purging. The gas chromatography column was used for separation. The retention time locking was used for qualitative analysis and the selected ion scanning mode (SIM) was used for detection. The detection limit and recovery rate of the method were analyzed. Results: The linear range of the method for the determination of six benzene homologues in human blood was 0.02-10.00 ng/ml, the correlation coefficient was 0.9927-0.9968, the detection limit was 0.006-0.016 ng/ml, the recovery rate of sample spiking was 84.39%-102.41%, and the precision of the method was 3.06%-6.90%. Conclusion: Purge and trap-gas chromatography-mass spectrometry can simultaneously determine the contents of six benzene homologues in human blood. The pretreatment method is simple, time-saving, and the method has low detection limit, which provides a scientific basis for the detection of benzene homologues in human body.

Beta‐cyclodextrin covalent organic framework coated silica composite as chiral stationary phase for high‐performance liquid chromatographic separation

AbstractA beta‐cyclodextrin covalent organic framework coated silica composite, namely beta‐cyclodextrin covalent organic framework@SiO2, was prepared by coating the beta‐cyclodextrin covalent organic framework onto a spherical aminized silica matrix and used as the chiral stationary phase for high‐performance liquid chromatography separation in both normal‐ and reversed‐phase modes. The beta‐cyclodextrin covalent organic framework@SiO2 packed column showed good separation performance towards positional isomers such as nitrotoluene and aminophenol, and benzene homologs in the reversed‐phase high‐performance liquid chromatography mode. While chiral drug molecules including omeprazole and lansoprazole could be also enantioseparated on beta‐cyclodextrin covalent organic framework@SiO2 packed column in the normal‐phase high‐performance liquid chromatography mode. Besides, the effects of mobile phase composition, column temperature, and other factors of high‐performance liquid chromatography separation on beta‐cyclodextrin covalent organic framework@SiO2 packed column were studied in detail. Moreover, the stability test of the beta‐cyclodextrin covalent organic framework@SiO2 packed column was also investigated. The results of continuous injections and monthly detection were basically identical, suggesting the excellent durability of the obtained high‐performance liquid chromatography column. This work indicated that beta‐cyclodextrin covalent organic framework@SiO2 composite could effectively separate different compounds in high‐performance liquid chromatography normal/reversed‐phase modes, making it a promising chiral stationary phase in the field of high‐performance liquid chromatography separation.

A novel process of low-temperature fractionation combined with extractive distillation for H2S removal from natural gas

H2S is a common component of natural gas. In order to meet the quality standards for U.S. commodity natural gas that contains less than 5.7 mg/m3 of H2S, it is necessary to process the natural gas to remove H2S. Since H2S will form azeotropes with ethane and propane in natural gas, it is impossible to achieve complete separation of H2S by ordinary distillation columns. Therefore, a novel low-temperature fractionation combined with extractive distillation process is proposed and designed, which can achieve the removal of H2S from sulfur-containing natural gas and obtain sweet gas(almost pure methane), ethane product and H2S gas. The process consists of three steps: demethanization with low temperature, deethanization with extractive distillation and H2S recovery. Extensive simulation and analysis have confirmed that extractive distillation using high molecular weight, high boiling point benzene homologs (toluene, o-Xylene, p-Xylene, m-Xylene) as extractant is a good method to separate ethane-H2S azeotrope. Furthermore, the effects of parameters such as the number of column stages, the reflux ratio, the location of feed stream inlet stage, the type of extractants, the inlet stage location of extractant, the molar flow rate of extractant on the product purity and the column duty have been studied, and the optimal applicable ranges of different parameters are finally determined. The simulation results show that o-Xylene is the best extractant for the separation of ethane and H2S. Under the economic optimization, the minimum total annual cost for the demethanizer is $952,611 per year and the minimum total annual cost for the deethanizer is $2,026,364 per year.

Preparation of Modified Porous Polyionic Liquid Microspheres and Their Application in High Performance Liquid Chromatography

Polymer microspheres have been widely used as a stationary phase in liquid chromatography. We characterized the properties of the novel polyionic liquid microspheres prepared and explored their application as a stationary phase in liquid chromatography. Cytosine, uracil, benzene, benzene homologs and alkaloids were successfully separated by liquid chromatography with the polymer microspheres as packing materials in the chromatographic column.

Electrospun polyacrylonitrile /MIL-53(Al) MOF@ SBA-15/ 4, 4ʹ-bipyridine nanofibers for headspace solid-phase microextraction of benzene homologues in environmental water samples with GC-FID detection

Metal-organic frameworks (MOFs) and mesoporous silica such as SBA-15 a family of mesoporous materials have received much attention for sampling and sample preparation in analytical chemistry. In this work, electrospun polyacrylonitrile /MIL-53(Al) MOF@ SBA-15/ 4, 4ʹ-bipyridine hybrid nanocomposite (PAN/MIL-53(Al)@SBA-15/BiPy2+2Cl−) was synthesised by hydrothermal method and investigated as a novel adsorbent for headspace solid-phase microextraction (HS-SPME) of benzene homologues, (Benzene, toluene, ethylbenzene, trimethylbenzene, styrene, and p-xylene), BETXs, with gas-chromatography-flam ionisation detector (GC-FID) analysis. Under optimized conditions, calibration graphs of analytes were linear in a concentration range of 0.01–250 μg L−1 with correlation coefficients higher than 0.9966. Limits of detection and This procedure directly determined BETXs in waters samples with recoveries ranging from 92.0 to 101.0%. The relative standard deviation (RSD) for single fiber and fiber to fiber microextraction (number of fibers = 5) were in the range of 1.8–3.2% and 3.6–5.3%, respectively. The purpose method successfully applied for microextraction and determination of 6 BETXs in water samples. The method possesses the advantages of simplicity, rapidity, cost-effectiveness, free from desorption solvent, sensitivity, and non-invasion; it provides an excellent alternative tool for determining BETXs in waters samples.

UiO-66 Selective Enrichment Integrated with Thermal Desorption GC-MS for Detection of Benzene Homologues in Ambient Air.

In this study, UiO-66 was selected as sorbent media packed in the tube to selectively enrich trace levels of benzene homologues such as benzene, toluene, and xylene (BTX) in ambient air prior to thermal desorption (TD)-GC-MS determination. A series of experiments were conducted to obtain the optimal TD conditions. The results indicated that the optimal TD parameters were as follows: desorption temperature of 180°C, desorption flow rate of 50 mL min−1, and desorption time of 30 min. Furthermore, the method based on UiO-66 enrichment integrated with TD-GC-MS for trace levels of BTX was successfully developed. It exhibited a good linearity (R2 > 0.99) in the range of 50–1000 ng, except for p, m-xylene in the range of 100–2000 ng, and achieved the recovery of 69.4–101.3%, and the relative standard deviation of 3.8–6.4%. The detection limits of BTX were 1.6–4.0 ng; according to 10 L of sampling volume, the method detection limits would be in the range of 0.16–0.40 µg m−3. Additionally, the method was successfully applied to determine BTX in indoor air and showed good selectivity and sensitivity. In summary, the findings in this work revealed that UiO-66 was an attractive adsorbent for selective enrichment trace levels of BTX compounds in ambient air, which was favorable for the subsequent detection by TD-GC-MS.

Emission Characteristics and Atmospheric Chemical Reactivity of Volatile Organic Compounds(VOCs) in Automobile Repair Industry

Volatile organic compounds (VOCs) emitted by the automobile repair industry are an important source of ozone precursors. However, the current reduction policy generally focuses on the emissions of VOCs, without considering their chemical reactivity. Based on an investigation of the development status of China's automobile repair industry, this study analyzes VOCs emission nodes in different sections of automobile repair enterprises. The amount and VOCs content of paint in each section was determined, and a material balance algorithm was used for sections with different VOCs quantities and compositions to analyze the emission characteristics of exhaust VOCs. The atmospheric reactivity of VOCs components was evaluated by calculating ozone generation potential (OFP). The results show that VOCs components produced by automobile repair paint are mainly benzene homologues, with butyl acetate and xylene the highest. Varnish is the largest contributor to VOCs emissions in automobile repair industries (92%), due to its high VOCs content and high dosage. The VOCs content of solvent-based coatings (22%) is higher than that of water-based coatings (3%). The application of water-based coatings leads to a remarkable reduction in VOCs emissions in automobile repair industries. A total of 49 VOCs components have been detected in gas from exhaust cylinders, with the top 10 VOCs components accounting for 97.9% of the total emissions. The main pollutants are aromatic hydrocarbons (10 types, 30.90%-69.30%), and OVOC (12 types) and halogenated hydrocarbons (22 types) were the second-highest contributors, with contribution rates of 8.82%-43.71% and 2.40%-25.00%, respectively. Aromatic hydrocarbon is the largest VOCs component emitted by automobile repair industries, but the main types of VOCs vary greatly in different studies. VOCs discharged by automobile repair industries have an average OFP value of 194.04 mg ·m-3 and an average SR value of 3.37 g ·g-1. The m/p-xylene component contributes the most to OFP (70.24%) and is the preferred pollutant in automobile repair industry. Aromatic hydrocarbons contribute a maximum of 99.29% to the OFP value and are also the most chemically reactive component. Although esters account for a large proportion of VOCs, their contribution to OFP is relatively low. Therefore, the automobile repair industry should focus on controlling the emission of aromatic hydrocarbons.

A stable nitrogen-rich zinc-based metal organic framework to investigate the structural similarity effect on the sorption efficiency of nitrogen-containing compounds

A stable porous zinc-based metal organic framework (MOF) containing nitrogen-rich bis-tetrazolate ligand was synthesized to study the role of similar structures concerning both extractive phase and the desired solutes to achieve greater sorption efficiency. With implementing a dispersive micro-solid phase extraction (d-µ-SPE) methodology, the sorption capability and influencing structural parameters i.e., porosity, surface area and interactions types were investigated for the synthesized zinc-bis-tetrazolate (ZnBT) MOF and compared with some synthesized sorbents such as MIL-101, MIL-101-NH2, cadmium naphthalene dicarboxylic acid dimethyl formamide [Cd(NDC)(DMF)], polyaniline and LiChrolut® EN. The sorption trends for triazines, as nitrogen-containing analytes, and benzene homologs, as nitrogen-free compounds, were evaluated. Accordingly, the synthesized ZnBT nanostructure was significantly dominant for the isolation of triazines. Moreover, the observed moderate sorption efficiency of nitrogen-rich MOF toward BTEX verifies the significant role of similar nitrogen-rich structure between MOF and triazines. Eventually, ZnBT was employed as the desired extractive phase for d-µ-SPE of triazines from environmental water samples followed by gas chromatography-mass spectrometric quantification. Under the optimized conditions, limits of detection (S/N = 3) and limits of quantification (S/N = 10) were in the ranges of 2–10 and 6–30 ng L−1, respectively. Also, the linear dynamic range (6–1000 ng L−1) and intra-day (3.3–5.2%) and inter-day (5.5–6.8%) relative standard deviations were comparable with other relevant reports. Among the selected triazines, a quantity of 51 ng L−1 of atrazine was quantified in the paddy water sample B. The obtained relative recovery values of 89–98% at 50 and 500 ng L−1 levels, confirmed the insignificant matrix effect.

The needle trap extraction capability of a zinc-based metal organic framework with a nitrogen rich ligand

A triple ring nitrogen rich ligand and along that a three-dimensional, zinc-based metal organic framework (MOF) were synthesized. The synthesized MOF was characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), energy dispersive X-ray spectroscopy and mapping, scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analyses. The extraction capability of the synthesized nanostructure was examined toward some analytes as model compounds. Properties such as porous structure and considerable surface area make it a suitable and efficient extractive phase. The extraction efficiency of the Zn-based MOF was evaluated for headspace needle trap extraction (HS-NTE) of benzene homologs (BTEX) as model compounds from aquatic media in conjunction with gas chromatography-mass spectrometry (GC-MS). To increase the sensitivity of the method, parameters including the extraction and desorption conditions were optimized. For some environmental water samples, acceptable relative recovery (RR) values at the concentration level of 20 ng L−1 ranged from 85 to 96% and showing no significant matrix effect.

Methoxy terminated poly dimethylsiloxane bonded stationary phase for reversed-phase liquid chromatography

In this work, a methoxy terminated poly dimethylsiloxane modified silica gel material was proposed as a novel stationary phase for reversed-phase liquid chromatography. With 5 μm silica gel as matrix, methoxy terminated poly dimethylsiloxane polymer was grafted by one step chemical bonding reaction. The obtained stationary phase was characterized by scanning electron microscopy, fourier transform infrared spectroscopy and element analysis. To our knowledge, this is the novel methoxy terminated poly dimethylsiloxane bonded stationary phase with good separation efficiency (42107-46988 plates/m for benzene homologues) and high stability (RSD is 0.08-5.09%). Comparing to other traditional columns of the same type, the proposed stationary phase has a wider polarity separation scale and shorter analysis time. In addition to the rapid separation of hydrophobic compound, such column also exhibited great potential in the separation of hydrophilic analytes.

Emissions Characterization of Volatile Organic Compounds and Health Risk Assessment in Two Fresh Furniture

The emissions of volatile organic compounds (VOCs) from two common furniture products including a dressing stool and a bedside cabinet were measured in an environmental chamber. The VOCs were collected by Tenax-TA tubes and measured by thermal desorption and gas chromatography (FID). 19 kinds of VOCs were quantitatively analyzed by the external standard method. The results showed that the VOCs concentrations emitted from the two kinds of furniture were quite different, but benzene homologues were the principal pollutant. The concentrations of VOCs released from the furniture showed decreases exponentially with time and it could be fitted well by a double-exponential decay model. The concentrations of VOCs increased rapidly and reached the maximums at around 1 or 2 h, and then declined with the slowdown of the release rate. Moreover, the potential VOCs release could be evaluated by the release parameters of this model. In addition, health risk assessment of benzene released from dressing stools and bedside cabinets was performed. The risk of benzene released from two kinds of furniture decreased with time. The R value of benzene released from the dressing stool at 72 h remained at least two orders of magnitude larger than 1 × 10−6, indicating a high risk of carcinogenesis. The study will provide a reliable reference in assessing VOCs emissions and health risks in fresh furniture.

Facile fabrication of silica@covalent organic polymers core-shell composites as the mixed-mode stationary phase for hydrophilic interaction/reversed-phase/ion-exchange chromatography

Covalent organic polymers (COPs) are a promising class of cross-linked polymeric networks that attracted extensive attention in separation and analysis fields. Exploring facile and convenient strategy to prepare COPs-based mixed-mode stationary phases for high performance liquid chromatography (HPLC) has seriously lagged and has never been reported. Herein, we describe a facile in-situ grow strategy for fabrication of silica@COPs core-shell composites (SiO2@TpBD-(OH)2) as a novel mixed-mode stationary phase for HPLC. Owing to the co-existing of abundant hydroxyl, carbonyl, imine, cyclohexyl groups, and benzene rings in the skeleton of COPs shell, the developed mixed-mode stationary phase exhibits hydrophilic interaction liquid chromatography (HILIC)/reversed-phase liquid chromatography (RPLC)/ion-exchange chromatography (IEX) retention mechanisms. The content of acetonitrile, pH value, and salt concentration in the mobile phase were investigated on SiO2@TpBD-(OH)2 packed column. In comparison to conventional single-mode columns, the SiO2@TpBD-(OH)2 column showed flexible selectivity, enhanced separation performance, and superior resolution for benzene homologues, polycyclic aromatic hydrocarbons, nucleosides and bases, and acidic organic compounds. The column efficiency of p-nitrobenzoic acid was up to 54440 plates per meter. The packed column also possessed outstanding chromatographic repeatability for six nucleosides and bases with the RSDs of 0.07–0.23%, 0.58–1.77%, and 0.31–1.23% for retention time, peak area, and peak height, respectively. Besides, the SiO2@TpBD-(OH)2 column offered baseline separation of multiple organic pollutants in lake water, which verified its great potential in real sample analysis. Overall, the silica@COPs core-shell composites not only provide a new candidate of mixed-mode stationary phases, but also extend the potential application of COPs in separation science.

Precisely Controlled Vertical Alignment in Mesostructured Carbon Thin Films for Efficient Electrochemical Sensing.

Two-dimensional carbon materials, incorporating a large mesoporosity, are attracting considerable research interest in various fields such as catalysis, electrochemistry, and energy-related technologies owing to their integrated functionalities. However, their potential applications, which require favorable mass transport within mesopore channels, are constrained by the undesirable and finite mesostructural configurations due to the immense synthetic difficulties. Herein, we demonstrate an oriented monomicelle assembly strategy, for the facile fabrication of highly ordered mesoporous carbon thin films with vertically aligned and permeable mesopore channels. Such a facile and reproducible approach relies on the swelling and fusion effect of hydrophobic benzene homologues for directional monomicelle assembly. The orientation assembly process shows precise controllability and great universality, affording mesoporous carbon films with a cracking-free structure over a centimeter in size, highly tunable thicknesses (13 to 85 nm, an interval of ∼12 nm), mesopore size (8.4 to 13.5 nm), and switchable growth substrates. Owing to their large permeable mesopore channels, electrochemical sensors based on vertical mesoporous carbon films exhibit an ultralow limit of detection (50 nmol L-1) and great sensitivity in dopamine detection.

Perylene Imide-Based Optical Chemosensors for Vapor Detection

Perylene imide (PI) molecules and materials have been extensively studied for optical chemical sensors, particularly those based on fluorescence and colorimetric mode, taking advantage of the unique features of PIs such as structure tunability, good thermal, optical and chemical stability, strong electron affinity, strong visible light absorption and high fluorescence quantum yield. PI-based optical chemosensors have now found broad applications in gas phase detection of chemicals, including explosives, biomarkers of some food and diseases (such as organic amines (alkylamines and aromatic amines)), benzene homologs, organic peroxides, phenols and nitroaromatics, etc. In this review, the recent research on PI-based fluorometric and colorimetric sensors, as well as array technology incorporating multiple sensors, is reviewed along with the discussion of potential applications in environment, health and public safety areas. Specifically, we discuss the molecular design and aggregate architecture of PIs in correlation with the corresponding sensor performances (including sensitivity, selectivity, response time, recovery time, reversibility, etc.). We also provide a perspective summary highlighting the great potential for future development of PIs optical chemosensors, especially in the sensor array format that will largely enhance the detection specificity in complexed environments.